Less boilerplate to test Redux middleware (in Jest)

test_mw.ts

type MWFixtures = Partial<{
    dispatch: Function;
    getState: Function;
    next: Function;
    action: object;
}>;

function mw_fixtures(fixtures: MWFixtures) {
    return fp.defaults({
        dispatch: jest.fn(),
        getState: jest.fn(),
        next: jest.fn(),
        action: { type: 'NOOP' },
    })(fixtures);
}

function test_mw(mw: Middleware, fixtures: MWFixtures) {
    fixtures = mw_fixtures(fixtures);

    fixtures.returned = mw(fixtures as any)(fixtures.next as any)(fixtures.action);

    return fixtures;
}

test('forced try_play_turn', () => {
    const { dispatch } = test_mw(mw_try_play_turn, {
      action: try_play_turn(true),
    });

    expect(dispatch).toHaveBeenCalledWith(play_turn());
});